## anonymous 5 years ago what is the exact value of cos 54* cos 8* + sin 53 * sin 8* *= Degrees

1. anonymous

That looks a lot like a trig identity.. $$cos(\theta - \phi)$$ probably.

2. anonymous

Well where doing functions of the sum of two angles... if that means anything Trigonnometric applications. of some sort and i know the chart is involved with the 30 45 60 sin , cos, tan kinda thing what is the thing next to beta.?

3. anonymous

Yeah, if you look in your book, or your notes you should see a formula that looks like this one except without the numbers. The formula you have here is the one for the sum/difference of two angles for cosine. $cos(\theta \pm \phi) = cos(\theta)cos(\phi) \mp sin(\theta)sin(\phi)$ In this case, $$\theta=53$$ and $$\phi=8$$. Since you are adding the product of the sines to the product of the cosines you just want to take the cosine of the difference between the two. 53-8 = 45. So the answer is the cos of 45 degrees.